Step 1:
-- Remove page encryption from dictionary (per table
encryption will be handled by storing crypt_data to page 0)
-- Remove encryption/compression from os0file and all functions
before that (compression will be added to buf0buf.cc)
-- Use same CRYPT_SCHEME_1 for all encryption methods
-- Do some code cleanups to confort InnoDB coding style
SYNTAX: ATOMIC_WRITES=['DEFAULT','ON','OFF']
Idea here is to be able to define innodb_doublewrite = 1 but with following rules:
ATOMIC_WRITES='DEFAULT' - if innodb_use_atomic_writes = 1, we do not write to doublewrite buffer the changes
if innodb_use_atomic_writes = 0, we write to doublewrite buffer
ATOMIC_WRITES='ON' - do not write to doublewrite buffer
ATOMIC_WRITES='OFF' - write to doublewrite buffer
Note that doublewrite buffer can't be used if innodb_doublewrite = 0.
